Engineer&#39;s slide-rule.



PATENTED DEG. 18, 1906'.

W. F. DOHERTY.

ENGINEERS SLIDE `RULE.

AIPLIGATION FILED JAN. 3, 1908.

UNITED sTATEs PATENT oEEIoE.

WILLIAM E. DoHEETY, oE SAN FRANCISCO, CALIFORNIA..l

ENGINEERS SLIDE-RULE'.

To all, whom, it may concern:

Be it known that I, WILLIAM F. DoIIEETY, acitiZen of the United States, residing in the cityg'andgcounty -of San Francisco, State of California, have invented certain new and useful Improvements in Engineers Slide-Rules; and I hereby declare the following to be a true, correct, and exact description of the same.

My invention relates to the class of engineers slide-rules.

In the use of these rules is it very difficult l obviated. For example, it is not conveniently located for operation, because not being on the non-sliding structure it does not present apermanent position on the rule, and, again, in registering the characteristic from time to time the operator is liable in moving the indicator to move the Manaheim slide itself, thereby destroying the registration of the line on its glass face with the number he has arrived at as the result of his mathematical procedure. In such a case he sacrifices accuracy for convenience in placing the decimal-point.

The object of my invention is to register or record the characteristic or decimal place conveniently and without endangering the accuracy or precision of the final answer sought.

To this end my invention conslsts in the novel improved slide-rule which I shall now describe by reference to the accompanying drawings, in Which- Figure 1 is a plan view of my improved rule. Fig. 2 is a cross-section, enlarged, on the line 9c a: of Fig. 1.

The general construction of the rule is the usual one, comprising a base A with elevated fixed scale a, a detachable scale B parallel with the fixed scale and secured to the base by suitable screws from underneath, a sliding scale C seated between the scales a and B, and a Manaheim slide D.

E is a digit-indicator consisting of a rotata- Speccaton off-Letters Patent. i Application filed January; 1906. Serial No. 294,378.

Patented Dec. 18,' 1 906.

ble disk having upon its face near its perimeterthenumeralsfromil to ;i;6.and0. In its best position lit is aboutone inch to the left of the median transverse line of the rule, and it is so disposed that its rim, which is preferably knurled, projects to the edge of the base A, which edge being a beveled one permits the finger to easily press said rim to turn the disk. y This position is one'whichfis the morst convenient for use, because the operator, holding with his left hand the lrule from'underneath, as is customary, can with the index-finger of said hand reach and turn the disk without difficulty to record the decimal place from time to time as it is found during his calculation.. v,

rIhe best manner of mounting the disk is that here shown. i A circular bed or depression is cut in the base A, the disk is dropped into it, whereby it is rotatably seated, and then by screwing down upon it the detachable scale B it is held in place without the necessity for any pivot-pin with any degree of pressure that may be desired, thereby rendering it as accurate in its operation as possible.

In order to definitely indicate that particular figure upon the disk which is intended to record the decimal-point, there is a cover F over the exposed part of the disk E, said expose only a single number on the disk. This cover is of course a stationary one and consists of a small plate secured in any suitable manner, as by means of screws, to the under side of the detachable scale B. It is slightly smaller in radius than the indicatordisk, so that the rim of the latter may be exposed for operative pressure.

From the foregoing description it will readconvenient position to be used by the operator with an easy movement of the first finger y of his left hand while holding the rule in the customary manner and without disturbing his hold on the rule or interfering with the operation of the other parts of the rule with his other hand. It will also be seen that the record of the characteristic or decimal place is accurate andprecise and cannot be disturbed by other manipulations, nor will its operation disturb them.

Having thus described the invention, what I claim as new, and desire to secure by Letters Patent, isl l. In an engineers slide-rule and in comcover having a sight-hole f in it, adapted to i ily be seen that the indicator is in the most IOO bination With its base and detachablescale, a decimal-.point-indicator disk rotatably mounted between said base and scale, with an arc of its circumference exposed foroperatlve ressure.

2. n an engineers slide-rule and in combination with its base and detachable scale, a decimal-point-indicator disk rotatably mounted between said base and scale, With an `arc otits circumference exposedffor operative pressure, and a iiXed cover Witha sight-hole, secured :to the scaleandlying over the disk.

3. Inanengineerfs slide-rule tliecoinbination of a base, havingfa circular depression .made in yits upper surface, ya decimal-.point- ;ind icator .disk seated Arotatably in said idepression, and a detachable scale, .secured `to v'the Abaseand bearing on Athe diskfto Ahold i t ,in .its seat.

4. In, an-enginee1s slide-rule @the l combina- .tion .of a base, ihaving ka circular ldepression `made in ,its `upper surface, va decimalfpointvindicator disk seated rotatably Ain said -dexpression, ,a ldetachable scale `.secured to the base over the disk, and a cover With a sight* hole, secured under the scale Vand partially overlying said disk.

5. Anengineers slide-rule including a base portion, a circular depression therein, a

correspondingly shaped decimal indicating plate seated in said depression, the edge of said plate projecting slightly beyond the outer edge of said base portion, a scale detachably secured to said base portion and .overlying a portion of lthe beforeeiuentioned xlndicatingfplate, .and va perforated cover between saiddetacliable scaleand saidindicating-plate, :thesame being secured `to .the detachable scaleatapoint to coincide ,with the Iposition .fof the ,indicating -plate ,When `the parts are assembled.

In Witness whereof `Lhave'hereunto set my hand.

WILLIAM F. 'DOHERTY Witnesses .J. COMPTQN,

D. B. RICHARDs. 

